Method of and an apparatus for forming a landscape border

ABSTRACT

A method of and an apparatus for forming a containment volume into which concrete, or another suitable landscape border material, may be added to form a landscape border involves positioning first and second elongate members such that the distance between them is substantially the same as the desired width of the landscape border. At least one connecting member configured to engageably interconnect with each of the first and second elongate members is positioned between the first and second elongate members to secure them at the desired landscape border width and thereby form a containment volume having a structural integrity that is sufficient to withstand the lateral forces imposed on the containment volume during addition of the concrete, or other landscape border material, into the containment volume.

RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. § 119(e) of U.S.Provisional Patent Application No. 60/514,942, filed Oct. 27, 2003.

TECHNICAL FIELD

The field of the present invention relates to a landscape edging systemand, more particularly, to a method of and an apparatus for separatingadjoining landscape, walkway, driveway, or other areas from one another.

BACKGROUND

Gardeners, landscapers, and homeowners frequently use border or edgingmaterial such as fences, logs, railroad ties, bricks, concrete blocks,and the like to provide a decorative edge for a landscape or garden.Such border or edging materials are also frequently employed tophysically separate landscape, walkway, driveway, or other areas fromone another.

Lengths of wood, corrugated metal bands, and decorative cement blocksare commonly used to provide a landscape border. Although wood providesan aesthetically pleasing landscape border, wood is subject to rot andinsect attack and thus decays over time. Ungalvanized metal bands aroundthe wood oxidize, rust, and tend to become bent or misshapen over time.Even galvanized metal bands eventually corrode once the protective zinccoating has been oxidized. Decorative cement blocks are inflexible andare difficult to install because of their weight. Also, each block costsapproximately $1, and a standard yard requires between about 300 andabout 500 cement blocks, making this an expensive method of forming alandscape border. Further, the use of cement blocks does not provide asubsurface barrier, so weeds, grass, flowers, or the like can grow intoadjoining areas of the yard. Consequently, all of these landscape bordermaterials must be replaced or repaired rather frequently and/or areexpensive and time-consuming to maintain and install.

Plastic landscape edging, on the other hand, is inexpensive, readilyavailable, flexible, and durable. As a result of the disadvantagesinhering in wood, metal, and cement landscaping materials and the uniqueadvantages of plastic, plastic landscape edging has become a landscapeedging material of choice for many homeowners. Plastic landscape edgingis commonly used to divide and separate different landscape areas, topreclude material in one area from spilling over into an adjacent area,and to prevent weeds, grass, flowers, or the like contained in one areafrom growing in an adjoining area. For example, plastic edging istypically used to divide grass landscape areas from adjoining gardenareas and to prevent grass from taking root in adjoining garden areas.Plastic edging also helps prevent garden bedding material from spillingonto the adjoining landscape area. The most prevalent materials used tofabricate plastic landscape edging today are inert, synthetic, andflexible plastics such as polyethylene and ethylene vinyl acetate.

Although landscape-edging components formed from inert, synthetic, andflexible plastics have many advantages, problems nevertheless occur intheir use. Conventional plastic landscape edging usually consists of asingle longitudinally extending strip of plastic material having a loweredge that is inserted into the ground at a predetermined depth and anupper edge, or rail that generally projects above the ground. The edgingis typically installed by digging a narrow trench, inserting the loweredge into the ground at a predetermined depth, refilling the trench, andcompacting the earth around the edging to secure its placement. Suchinstallation normally maintains the edging in its intended position fora period of time.

As time passes, however, the environment and other factors actively workagainst the edging's remaining in its original position. The edging maybe walked on, bumped, kicked, shoved aside, or otherwise engaged in sucha manner that it is displaced from its original position. For example,lawn mowers or tractors may drive over the edging, causing displacementor damage. Further, the winter effects of frost heave or the freezingand thawing action of the earth surrounding the edging also cause edgingdisplacement and damage. The ground retains moisture in the fall thatfreezes during the winter due to the dropping temperatures. Water is oneof the few materials having a coefficient of volume expansion thatincreases as temperature decreases, and the ground accordingly expandswith frozen moisture in the winter. This expansion has the effect ofcompressing and heaving the landscape edging, and as a result the edgingoften breaks or is laterally or vertically displaced. When springarrives, plastic landscape edging is often found to have buckled upwardsand protruded from the ground during the winter in response to frostheave, especially where adjacent strips of edging are connected to oneanother. As temperatures rise in the spring and summer months, themoisture beneath the ground surface melts, changing the volume of thesubsurface ground adjoining the edging. As the seasons alternate, thelandscape edging is repeatedly exposed to a variety of forces arisingfrom changing soil volumes that, over a prolonged period of time, causethe edging to become dislodged or damaged.

One prior art attempt at circumventing the problems that exist in theseprior art landscape-edging systems involves installing a concretelandscape border. Concrete borders are exceptionally durable andlow-maintenance. Also, they create an impenetrable barrier through whichweeds, grass, flowers, or the like cannot grow, thus preventing plantsin one area from growing into an adjoining area. One method ofinstalling a concrete landscape border involves employing a constructioncompany to (1) build customized frames that define the desired shape ofthe landscape border and (2) pour concrete into the forms. Customizedforms are typically constructed of 2×4s nailed together and then stakedto the ground, to ensure that the forms do not move while the concreteis being poured or is hardening. This process typically requires a crewof between two and three people and costs approximately $18 per linearfoot of concrete landscape border.

A second, less expensive method of installing a concrete landscapeborder involves employing a curbing company that extrudes concrete inthe desired shape along the desired length of the landscape border.Because this process does not require the construction of customizedforms, it can typically be completed by a smaller crew. Consequently,the average cost is approximately $6 per linear foot of concretelandscape border.

Although concrete landscape borders offer exceptional durability andprovide an impenetrable barrier to weed growth, most homeowners cannotafford the high costs associated with hiring a crew to build or extrudea concrete landscape border.

The present inventors have thus recognized a need for an easier and moreaffordable method of and apparatus for forming a concrete landscapeborder.

SUMMARY

The present invention is directed to a method of and an apparatus forusing landscape-edging members to form a containment volume into whichconcrete, or other suitable landscape border materials, may be added toform a landscape border. A preferred method involves positioning a firstelongate member and a second elongate member parallel to one anothersuch that the distance between the first and second elongate members issubstantially the same as the desired width of the landscape border. Thefirst and second elongate members are also positioned adjacent to aground surface along a portion of the desired length of the landscapeborder. At least one connecting member configured to engageablyinterconnect with each of the first and second elongate members is thenpositioned between the first and second elongate members to secure themat a separation forming the desired landscape border width and therebyform a containment volume having a structural integrity that issufficient to withstand the lateral forces imposed on the containmentvolume when the material whose presence forms a landscape border isplaced into the containment volume. A preferred exemplary material whosepresence forms a landscape border is concrete. Once the landscape bordermaterial is placed in the containment volume, the material is allowed toharden, if necessary, to form the landscape border. Then, the connectingmember(s) and the first and second elongate members may be removed fromthe formed landscape border.

A preferred apparatus includes first and second elongate members, eachof which preferably has an elongate side member height that is greaterthan or equal to the desired height of the landscape border, andmultiple connecting members configured to engageably interconnect witheach of the first and second elongate members. The first and secondelongate members and the connecting members are preferably formed of aplastic such as polyethylene, polypropylene, or ethylene vinyl acetate.Other elastomeric, polymeric, or synthetic materials are also suitablefor forming the landscape edging members.

Additional aspects and advantages of this invention will be apparentfrom the following detailed description of preferred embodiments, whichproceeds with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic drawing of a preferred embodiment of the landscapeborder forming apparatus.

FIGS. 2 a, 2 b, and 2 c are respective isometric, front elevation, andside view schematic drawings of a preferred embodiment of the connectingmember.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In a preferred application of a method of and an apparatus for forming acontainment volume into which concrete, or any other landscape bordermaterial, may be added to form a landscape border, a landscape borderforming apparatus 10 preferably includes a first elongate member 12, asecond elongate member 14, and at least two connecting members 16 asshown in FIG. 1. Each of first and second elongate members 12 and 14includes a lower portion 18 and an upper portion 24. When positioned toform a containment volume 28, lower portion 18 is situated adjacent to aground surface 30 along at least a portion of the desired length of thelandscape border such that upper portion 24 extends above ground surface30. For example, lower portion 18 may be placed adjacent to a gravel,sand, or dirt ground surface 30. Optionally, lower portion 18 may extendbelow ground surface 30.

First and second elongate members 12 and 14 are positioned parallel toone another such that a separation distance 32 between them issubstantially the same as the desired width of the landscape border. Anexemplary preferred a separation distance 32 is between about 2 inches(5.08 cm) and about 6 inches (15.24 cm). First and second elongatemembers 12 and 14 have an elongate member height 33 that is equal to orgreater than the desired height of the landscape border. In a preferredembodiment, the elongate member height is between about 2 inches (5.08cm) and about 6 inches (15.24 cm). Further, in a preferred embodiment,elongate member height 33 is between about 0.25 inch (0.635 cm) andabout 2 inches (5.08 cm) greater than the desired height of thelandscape border.

Connecting member 16 is configured to engageably interconnect with eachof first and second elongate members 12 and 14. When connected to firstand second elongate members 12 and 14, respectively, connecting member16 secures the elongate members at a separation distance 32 and therebyforms containment volume 28 into which may be placed a material whosepresence forms a landscape border.

A variety of means for interconnecting connecting member 16 with each offirst and second elongate members 12 and 14 may be employed. In apreferred embodiment, shown in FIGS. 1, 2 a, 2 b, and 2 c, connectingmember 16 includes two longitudinally disposed slots 34 extending upwardfrom a bottom edge 36 of connecting member 16. Longitudinally disposedslot 34 is configured to receive, engage, abut, or otherwise connectwith at least a portion of the corresponding first and second elongatemembers 12 and 14. Because longitudinally disposed slot 34 and first andsecond elongate members 12 and 14 interconnect, they are preferably ofcomplementary shapes such that their interconnection forms a snug fit.In the exemplary preferred embodiment shown in FIG. 1, longitudinallydisposed slot 34 has a width of about 0.125 inch (0.318 cm) and a heightof about 3 inches (7.62 cm), and each of first and second elongatemembers 12 and 14 has a width of about 0.09 inch (0.229 cm). However,these dimensions are merely exemplary and the fit of connecting member16 and first and second elongate members 12 and 14 may vary. Thepreferred snug fit between connecting member 16 and first and secondelongate members 12 and 14 preferably may ensure that containment volume28 has a structural integrity that is sufficient to withstand thelateral forces imposed during pouring of concrete, or any otherlandscape border material, into containment volume 28.

Connecting member 16 preferably forms an expansion joint in the concretelandscape border to provide an expansion allowance. As described above,the volume of the concrete, or other landscape border material, formingthe landscape border changes slightly depending on weather conditions.In the cold of winter, the concrete contracts slightly; in the heat ofsummer, the concrete expands slightly. If no expansion joints are builtinto the landscape border, the border may crack or split during thesechanges in volume. Thus a preferred embodiment of landscape borderforming apparatus 10 includes an expansion control joint. Whenconnecting member 16 is interconnectively adjoined to first and secondelongate members 12 and 14 and when concrete, or any other landscapeborder material, is poured into containment volume 28, the concreteflows into and fills the open areas, including a hollow 52; however, theconcrete, or other landscape border material, does not fill the areaoccupied by connecting member 16. Once the concrete hardens andconnecting member 16 is removed, the areas that are not filled withconcrete form expansion control joints that prevent the concretelandscape border from cracking or splitting as a result of its naturalexpansion and contraction. An exemplary preferred embodiment includes anexpansion control joint having a thickness of about 1.27 cm (0.5 inch).

In one preferred exemplary embodiment, connecting member 16 includeshollow 52, as shown in FIGS. 2 a and 2 b. Hollow 52, in this exemplarypreferred embodiment is the unshaped opening in connecting member 16that forms a passage through which the added material may flow. Hollow52, as shown in FIGS. 2 a and 2 b, has a length of about 4 inches (10.16cm) and a height of about 2 inches (5.08 cm). When connecting member 16is interconnectively adjoined to first and second elongate members 12and 14 and when concrete is poured into containment volume 28, theconcrete flows into and fills hollow 52. Once the concrete hardens, theportion of the resulting landscape border formed by hollow 52 maintainsthe structural integrity and continuity of the landscape border formedon either side of connecting member 16. However, connecting members 16can lack hollow 52 and instead form a larger expansion joint.

As shown in FIGS. 2 a and 2 b, connecting member 16 may include anergonomic handgrip 56 that increases the ease with which the user mayremove connecting member 16 from the formed landscape border.

As shown in FIG. 1, landscape border forming apparatus 10 and the methodof a preferred embodiment may include the use of stakes 54, which arepositioned adjacent to first and second elongate members 12 and 14 andpushed into ground surface 30 to provide a stabilizing barrier thatkeeps first and second elongate members 12 and 14 from moving during thelateral forces imposed during pouring of concrete, or other landscapeborder material, into containment volume 28.

An exemplary preferred landscape border forming apparatus 10, as shownin FIGS. 1, 2 a, and 2 b, has the following measurements: TABLE 1Landscape Border Forming Apparatus Measurements Elongate MemberMeasurements: Thickness: 3 inches (7.62 cm) Height: 3 inches (7.62 cm)Length: 6 feet (1.83 m) Recess Width: 0.125 inch (0.318 cm) ConnectingMember Measurements: Thickness: 0.125 inch (0.318 cm) Height: 6 inches(15.24 cm) Length: 0.09 inch (0.229 cm) Hollow Height: 2.5 inches (6.35cm) Hollow Length: 5.88 inches (14.94 cm)

A preferred method of installing landscape border forming apparatus 10involves positioning first and second elongate members 12 and 14parallel to one another at a separation distance 32 and adjacent toground surface 30 along at least a portion of the desired length of thelandscape border such that upper portion 24 extends above ground surface30. Connecting member 16 is then positioned to slidably, engageablyinterconnect with each of first and second elongate members 12 and 14such that connecting member 16 secures first and second elongate members12 and 14 such that the distance between them defines a separationdistance 32, which is substantially the same as the desired width of thelandscape border. Affixation of first and second elongate members 12 and14 forms containment volume 28. Next, concrete, or another materialhaving sufficient mechanical integrity to form a solid or semisolidlandscape border, is deposited into containment volume 28. The concreteor other material is allowed to harden, and then landscape borderforming apparatus 10 is removed from the resulting landscape border. Theremoval step preferably involves lifting, sliding, or otherwise removingconnecting members 16 and peeling or otherwise removing first and secondelongate members 12 and 14 from the landscape border. Because landscapeborder forming apparatus 10 is preferably reusable, the entire processcan be repeated to extend the length of the landscape border.

Although these methods may be practiced using only one first elongatemember 12 and one second elongate member 14 and two connecting members16, an alternative embodiment involves aligning a plurality of engaging,abutting, or interconnected elongate members 12 and 14 along the lengthof the desired landscape border adjacent to or beneath ground surface30. In this alternative embodiment, the ends of the plurality ofelongate members 12 and 14 are preferably of a shape that permits theirengageable interconnection. As stated above, a variety of means forinterconnecting elongate members 12 and 14 may be employed, such as, forexample, complementary shapes, a tongue-and-groove connection, and pins.

In another alternative embodiment, landscape border forming apparatus 10may be constructed such that its use forms a decorative, angled, orshaped landscape border. For example, first and second elongate members12 and 14 may have a graduated thickness along their height thatprovides an aesthetically pleasing angling of the resulting landscapeborder. Alternatively, first and second elongate members 12 and 14 mayhave sufficient stiffness such that their shape is curved or otherwisedecorative. Alternatively, one or both of elongate members 12 and 14 mayinclude preformed corners.

Landscape border forming apparatus 10 is preferably formed by extrudingand molding a synthetic material that is resilient, flexible, inert,ultraviolet- (UV) resistant, and capable of withstanding wide variationsin ambient temperature and humidity. To this end, landscape borderforming apparatus 10 is preferably formed of a plastic material such aspolyethylene, polypropylene, linear high-density polyethylene, orethylene vinyl acetate. However, other elastomeric, polymeric, orsynthetic materials are also suitable for forming landscape borderforming apparatus 10. The chosen elastomeric, polymeric, or syntheticmaterial for forming landscape border forming apparatus 10 is preferablysufficiently durable that it can be reused numerous times, permittingthe user to form unlimited lengths of landscape border. Further, thechosen elastomeric, polymeric, or synthetic material for forminglandscape border forming apparatus 10 is preferably inexpensive,allowing the average homeowner to have sufficient funds to purchase anduse landscape border forming apparatus 10. Also, the chosen elastomeric,polymeric, or synthetic material for forming landscape border formingapparatus 10 is preferably highly flexible such that landscape borderforming apparatus 10 can easily be positioned to conform to the contoursof the adjacent lawn area. Lastly, a preferred elastomeric, polymeric,or synthetic material for forming landscape border forming apparatus 10is preferably water-resistant such that apparatus 10 can be rinsed withwater to quickly and easily remove residual concrete from apparatus 10following its use.

Landscape border apparatus 10 may be treated with a surface preparationthat affects the water-resistance, peelability from the concretelandscape border, UV-resistance, or other mechanical property oflandscape border apparatus 10. For example, landscape border apparatus10 may be treated with a Teflon-impregnated coating that facilitateslandscape border apparatus 10's resistance to adhesion with the concretepoured into landscape border apparatus 10.

One significant drawback to most plastics finding application inlandscape border design is their relatively rapid breakdown caused byexposure to UV radiation. Thus landscape border forming apparatus 10 maybe protected or shielded from UV radiation by treatment with aUV-resistant coating. However, because landscape border formingapparatus 10 is usually removed from the formed concrete landscapeborder, and is thus not continually exposed to UV radiation, applicationof this UV-resistant coating is merely optional.

Landscape border forming apparatus 10 is also preferably sufficientlyflexible and structurally configured to permit packaging in a coiledfashion. See, for example, U.S. Pat. No. 5,519,970 to Reum et al., whichdiscloses lawn or landscape edging members that lend themselvesparticularly well to being packaged in coiled fashion.

Landscape border forming apparatus 10 of the preferred embodiment mayoffer various advantages over prior art methods of forming landscapeborders. First, homeowners may inexpensively and easily form adecorative and durable concrete landscape border having any desiredshape, e.g., around flowerbeds, along driveways, and encircling trees.Because landscape border forming apparatus 10 is inexpensive tomanufacture and easy to use, homeowners can use the apparatus topractice the method themselves, greatly reducing the cost of the processas compared to prior art methods of forming a concrete landscape border.Also, because landscape border forming apparatus 10 can be reusednumerous times, homeowners need only purchase a single do-it-yourselfkit in order to form an unlimited length of concrete landscape border.Second, the formation of a concrete border eliminates the need fortime-consuming and troublesome lawn edging, saving homeowners additionaltime and money. Third, concrete landscape borders provide an excellentand impenetrable barrier that prevents weeds, grass, flowers, or thelike located in one area from growing into an adjoining area. Fourth,concrete landscape borders are extremely durable in all weatherconditions and require minimal maintenance. Additionally, the expansionallowance described above ensures that the concrete landscape borderwill survive the extreme temperature fluctuations of certain climates.For all of these reasons, landscape border forming apparatus 10 and themethods of using landscape border forming apparatus 10 far exceedanything currently commercially available in both ease of use andcost-effectiveness.

It will be obvious to those having skill in the art that many changesmay be made to the details of the above-described embodiments withoutdeparting from the underlying principles of the invention. The scope ofthe present invention should, therefore, be determined only by thefollowing claims.

1. A method of forming a containment volume that accepts introduction ofa material for forming a border having a desired length, height, andwidth, comprising: positioning a first elongate member and a secondelongate member adjacent to a ground surface along at least a portion ofthe desired length of the border such that a distance between the firstand second elongate members is substantially the same as the desiredwidth of the border, each of the first and second elongate membershaving an elongate member height that is greater than or equal to thedesired height of the border; and positioning a connecting memberconfigured to engageably interconnect with each of the first and secondelongate members such that the connecting member secures the first andsecond elongate members at a separation distance forming the desiredborder width, the connecting member spanning the distance between thefirst and second elongate members and forming a containment volumehaving a structural integrity that is sufficient to withstand theintroduction of the added material into the containment volume.
 2. Themethod of claim 1, in which the process of positioning a connectingmember includes positioning at least two connecting members such thatthey secure the first and second elongate members at the desired borderwidth and thereby form the containment volume.
 3. The method of claim 1,in which engageable interconnection between the first and secondelongate members and the connecting member is achieved by slidablyengaging respective first and second elongate members with respectivefirst and second longitudinally disposed recesses that extend upwardfrom a bottom edge of the connecting member.
 4. The method of claim 1,in which the engageable interconnection between the first and secondelongate members and the connecting member is achieved by the use of anapparatus selected from a group consisting essentially of complementaryshapes, a tongue-and-groove connection, pins, and combinations thereof.5. The method of claim 1, further comprising facilitating removal of theconnecting member from the border by providing an ergonomic handgrip inthe connecting member.
 6. The method of claim 1, in which the addedmaterial is concrete.
 7. The method of claim 1, further comprisingremoving from the border the first and second elongate members and theconnecting member without significantly impacting a structural integrityproperty of the border.
 8. The method of claim 1, in which the first andsecond elongate members and the connecting member are formed by one ofextrusion and molding of a synthetic material.
 9. The method of claim 1,in which the first and second elongate members and the connecting memberare formed of a plastic material selected from a group consistingessentially of polyethylene, polypropylene, and ethylene vinyl acetate.10. The method of claim 1, in which the first and second elongatemembers and the connecting member are formed of a material selected froma group consisting essentially of an elastomeric, a polymeric, and asynthetic material.
 11. The method of claim 1, in which the first andsecond elongate members and the connecting member are at least partiallycoated with one of a UV-resistant coating, a water-resistant coating, asurface treatment that facilitates removal of one of the first andsecond elongate members and the connecting member from the formedborder, and a combination thereof.
 12. The method of claim 1, in whichthe shape of the connecting member creates an expansion joint in theformed border.
 13. A concrete landscape border formed by the method ofclaim
 1. 14. An apparatus for forming a containment volume that acceptsaddition of a material for forming a border having a desired length,height, and width, comprising: a first elongate member and a secondelongate member, each elongate member being positioned adjacent to aground surface along at least a portion of the desired length of theborder and such that the first and second elongate members are spacedapart by an elongate member distance that is substantially the same asthe desired width of the border, each of the first and second elongatemembers having an elongate member height that is greater than or equalto the desired height of the border; and a connecting member configuredto engageably interconnect with each of the first and second elongatemembers such that the connecting member spans the distance between firstand second elongate members and secures the first and second elongatemembers at the elongate member distance, thereby forming a containmentvolume having sufficient structural integrity to withstand lateralforces imposed on the containment volume during the introduction of theborder-forming material into the containment volume.
 15. The apparatusof claim 14, further including multiple connecting members.
 16. Theapparatus of claim 14, in which the connecting member includes first andsecond longitudinally disposed recesses that extend upward from a bottomedge of the connecting member and that are of a size that permitsengagement with each of the first and second elongate members.
 17. Theapparatus of claim 14, in which the connecting member includes anergonomic handgrip.
 18. The apparatus of claim 14, in which the addedmaterial is concrete.
 20. The apparatus of claim 14, in which the firstand second elongate members and the connecting member are formed of aplastic material selected from a group consisting essentially ofpolyethylene, polypropylene, and ethylene vinyl acetate.
 21. Theapparatus of claim 14, in which the first and second elongate membersand the connecting member are formed of a material selected from a groupconsisting essentially of an elastomeric, a polymeric, and a syntheticmaterial.
 22. The apparatus of claim 14, in which the first and secondelongate members and the connecting member are at least partially coatedwith a UV-resistant coating.
 23. A method of installing a landscapeborder having a desired length, height, and width, comprising:positioning a first elongate member and a second elongate memberadjacent to a ground surface along at least a portion of the desiredlength of the landscape border such that a distance between them issubstantially the same as the desired width of the landscape border,each of the first and second elongate members having an elongate memberheight that is greater than or equal to the desired height of thelandscape border; positioning a connecting member configured toengageably interconnect with each of the first and second elongatemembers such that the connecting member secures the first and secondelongate members at the elongate member distance and thereby establishesa containment volume having a structural integrity property; adding tothe containment volume a material whose presence forms a landscapeborder, the structural integrity of the containment volume beingsufficient to enable the containment volume to withstand the addition ofthe material; and removing from the landscape border the first andsecond elongate members and the connecting member without significantlyimpacting a structural integrity property of the landscape border.